10 Energy Consumption

Overview of Chapter 10 Energy Consumption and Policy Energy Efficiency and Conservation Electricity, Hydrogen and Energy Storage Energy Policy Energy and Climate Change

Energy Consumption and Policy No energy sources are truly clean All humans activities require energy Heat & cool buildings Illuminate buildings and streets Plant, harvest, & ship food 100 years ago energy sources were local Wood, peat, dung Now they are worldwide Fossil fuels, nuclear energy, electricity

Energy Consumption and Policy Advantages of energy source How concentrated it is Versatility Safety Availability Disadvantages of energy source Hazard potential Environmental damage Cost See Table 10.1 in text for details

Energy Consumption Worldwide Differs between developing and developed nations 20% of world’s population use 60% of the world’s energy sources

Energy Consumption in US

Energy Efficiency Amount of available energy in a source that is transformed into useful work Ranges from 0–100% Natural gas (cooking) ~100% Natural gas (electricity) ~60 Incandescent bulbs ~2-3% Fluorescent bulbs ~10% Light-emitting diodes ~20% Pictured here

Energy Intensity Energy Intensity- energy use per $ of GDP

Energy Efficiency Super-insulated buildings use 70-90% less energy NAECA sets national standards for appliances Refrigerators built post- 2001 are 75% more efficient than those build in 1975 Payback of $135/yr!

Energy Efficiency - Commercial Buildings High-performing buildings pay for themselves Energy costs = 30% of budget

Energy Efficiency- Power Company Demand-side Management Decreases demand for electricity Cash rewards/incentives to customers who install energy-efficient technologies Energy companies may give away free energy- efficient appliances, light bulbs, etc. Benefits both customer and electric company

Energy Efficiency - Transportation Most energy in gasoline is wasted Energy lost in combustion to heat Energy lost in braking Energy lost in friction with road Energy lost in moving weight of car (not passengers)

Energy Efficiency - Transportation Modern Vehicle Design Use of Kevlar and plastics to reduce weight Gasoline-electric hybrid engines (Prius) Regenerative braking recaptures lost energy Operate at lower temperatures New Laws By 2020, all passenger vehicles must have ave fuel efficiency of 35 mpg Including minivans, light trucks and SUVs

Energy Efficiency - Industry Cogeneration- production of two useful forms of energy from the same fuel Most effective on small scale

Energy Conservation Requires a change in behaviors and practices Reduce commute length Use public transportation or bike to work Turn off lights when not in use Reduce temperature on thermostat at night Some changes would be difficult - e.g., removing subsidies Allow product prices to reflect true cost of production (including energy costs) Increase price of gasoline to represent true price

Energy Conservation

Electricity The flow of electrons in a wire Can be generated from almost any energy source Energy source spins a turbine Turbine turns a generator Bundle of wires spin around a magnet or vice versa Spinning causes electrons to move in a wire = electricity

Electricity Source of electricity can be hundreds of miles away Environmental impacts are far away from those who use the energy

Hydrogen and Fuel Cells Hydrogen gas (H2) Comprised of two hydrogen molecules Large amounts of available energy Explodes when combined with oxygen releasing energy and forming water

Hydrogen as a Fuel Source Advantages Very high energy density Can be produced from any electrical source Electrolysis (see illustration on next slide) No greenhouse gases and few other pollutants Can be use in vehicles Disadvantages Highly volatile (requires special storage) Relatively inefficient

Electrolysis

Hydrogen Fuel Cell Fuel cell Device that directly converts chemical energy into electricity Requires hydrogen from a tank and oxygen from the air Similar to a battery, but reactants are supplied from outside source

Future Applications of Fuel Cells Hydrogen Fuel Cells Vehicles H not yet readily available as fuel source 61 H fueling stations in US

Energy Storage Many energy resources are not available when we want them Too little: Solar and wind can be intermittent Too much: Large coal and nuclear plants are most efficient with constant energy output Solution = storage of unused energy Less than 100% efficient With each conversion, less energy is available

Energy Storage Superconducting Magnetic Energy Storage Compressed Air Energy Storage Electrochemical Energy Storage (Batteries) Pumped Hydrogen Storage Thermal Energy Storage Kinetic Energy Storage (Flywheel)

US Energy Policy Objective 1: Increase Energy Efficiency and Conservation Requires many unpopular decisions Examples Decrease speed limit to conserve fuel Eliminate government subsidies Objective 2: Secure Future Fossil Fuel Energy Supplies 2 oppositions: environmental and economic

US Energy Policy Objective 3: Develop Alternative Energy Sources Who should pay for this? Gas taxes? Objective 4: Meet the First Three Objectives Without Further Damage to the Environment